I do not think it is such a disaster. However double clicking does not work. Maybe it should.

You said right at the end of your discourse There will be references when selecting, and no one will adjust the nodes after the connection.no-one? that is a bit of an all encompassing statement.

Rectangular, elliptical selections in 2.8 already require Return to lose the handles and fix the selection. Freeselect now works a bit more like the Scissors tool which already has movable nodes and Return (or double click) to fix, so a bit of uniformity there.

It does fit in with some of the other re-vamped tools which do not have a confirmation dialogue. Gradient and Warp Transform for example. These also require Return to complete the tool.

In fact, your operation is still avoiding this new feature, so this new feature is not convenient.
As long as a lot of people give advice, they will be accepted.

"Transform tools can use path borders"
This was my suggestion, but it was summed up as "repeated recommendations", but a few days later someone asked for it! Then the proposal was accepted! Now can use this feature